During the step of braking, in the brakes of a road vehicle, the kinetic energy of the road vehicle is converted into heat, which is then disposed of into the external environment. It is important to prevent the temperature of the brakes from becoming too hot because an overheating of the brakes may lead to a corresponding overheating of the braking system actuating liquid, which can “boil” and therefore loose at least part of its hydraulic features; the overheating of the braking system actuating liquid is particularly negative because it determines a loss (which may be even very high) of the braking power which can be developed by the braking system, and thus determines a condition of extreme danger.
In a high-performance road, the brakes (and particularly, the front brakes) may require, in some operating situations (typically in the case of driving on a racing track), supplementary cooling to avoid overheating; such a supplementary cooling is guaranteed by specific cooling duct, which originate from air intakes obtained through the body (typically through the front fenders, in case of front brake cooling) and end near the brakes to convey the cooling air towards the brakes themselves.
However, it has been noted that the air intakes which feed the cooling ducts of the brakes determine a worsening of the aerodynamic penetration coefficient of the road vehicle, while the supplementary cooling of the brakes guaranteed by such air intakes is only necessary in particular conditions during the life of the vehicle, which are generally not very frequent. In order to solve this drawback, patent DE3834119A1 suggests to couple a shutter to each air intake of a cooling duct of a brake, which shutter is mobile so as to move between a closing position, in which the shutter closes the air intake and prevents the entrance of air into the cooling duct and thus improves the aerodynamic penetration of the road vehicle, and an opening position, in which the shutter leaves the air intake unobstructed and allows the entrance of air into the cooling duct. An actuating device controls the movement of the shutters which close the air intakes of the cooling ducts to keep the air intakes normally closed and open the air intakes only in case of actual need (i.e. during high intensity braking).
Similarly, patent application GB2269144A1, patent application DE4229945A1 and patent application DE42431288A1 describe a road vehicle provided with a cooling duct for cooling a brake and comprising: an air intake arranged at the inlet of the cooling duct; a shutter, which is mobile so as to move between a closing position and an opening position; and an actuating device, which controls the movement of the shutter and thus moves the shutter between the closing position and the opening position. The shutter is normally closed and therefore the actuating device must be actuated to move the shutter from the closing position to the opening position.
The solution introduced in patent applications DE3834119A1, GB2269144A1, DE4229945A1 and DE42431288A1 has some drawbacks, because it does not guarantee that the front brakes are always adequately cooled also in case of malfunctioning of the actuating device which controls the movement of the shutters which close the air intakes of the cooling ducts.